1. Field of the Invention
The present invention relates to apparatus for treating water, such as water softeners; and more particularly to a valve assembly for controlling the regeneration of the treatment medium in such apparatus.
2. Description of the Related Art
It is quite common for water drawn from a well to be considered “hard” in that the water contains di-positive and tri-positive ions which have leached from mineral deposits in the earth. Such ions form insoluble salts with common detergents and soaps producing precipitates that increase the quantity of detergent or soap required for cleaning purposes. When hard water is used in boilers and other equipment, evaporation results in the precipitation of insoluble residues that accumulate as scale and adversely affect the operation of that equipment.
It is standard practice to install a water softener in the plumbing system of a building that is supplied with hard water. The most common kind of water softener is an ion exchange apparatus that has a tank containing a resin bed through which the hard water flows to remove undesirable minerals and other impurities. Binding sites in the resin bed initially contain positive ions, commonly unipositive sodium or potassium ions. As hard water enters the bed, competition for the binding sites occurs. The di-positive and tri-positive ions in the hard water are favored due to their higher charge densities and displace the unipositive ions. Two or three unipositive ions are displaced for each di-positive or tri-positive ion, respectively.
The capacity of the resin bed to absorb minerals and impurities is finite and eventually ceases to soften the water when a large percentage of the sites become occupied by the di-positive and tri-positive ions. When this occurs, it is necessary to recharge or regenerate the resin bed by flushing it with a regenerant, typically a solution of sodium chloride or potassium chloride. The concentration of unipositive ions in the regenerant is sufficiently high to offset the unfavorable electrostatic competition and the binding sites are recovered by unipositive ions. The interval of time between regeneration periods during which water softening takes place is referred to as a service mode of operation.
Regeneration of water softeners is controlled by a valve arrangement that is automatically operated a motor through the standard regeneration cycle to flush, regenerate, and rinse the resin bed. A controller activates the motor based on the length of time since the previous regeneration, the amount of water that was treated, or the conductivity of the resin bed which indicates the remaining treatment capacity.
The valve arrangement is housed in a body with external connections for a water inlet, a water outlet, a regenerate reservoir, and a drain line. The body also includes a fitting to which the resin tank attaches. The external connections and the fitting communicate with a plurality of passages in the body that are selectively connected to one another by the operation of the valve arrangement. Heretofore, the valve body consisted of many different sections that were molded or machined separately before being fastened together to form the complete body. An example of one type of a prior valve assembly is described in U.S. Pat. No. 5,910,244. The complexity of the external connections and internal passages made reducing the number of valve body sections difficult without adding to the machining steps and thus the cost of the body.
Thus it is desirable to design a valve body in a way that reduces the number of parts, while facilitating casting the parts in a manner that eliminates subsequent machining.